Systems and methods for calibrating image capturing modules

Abstract

A system and method for calibrating a machine vision system on the undercarriage of a rail vehicle while the rail vehicle is in the field is presented. The system enables operators to calibrate the machine vision system without having to remove the machine vision system from the undercarriage of the rail vehicle. The system can capture, by a camera of an image capturing module, a first image of a target. The image capturing module and a drum can be attached to a fixture and the target can be attached to the drum. The system can also determine a number of lateral pixels in a lateral pitch distance of the image of the target, determining a lateral object pixel size based on the number of lateral pixels, and determining a drum encoder rate based on the lateral object pixel size. The drum encoder rate can be programmed into a drum encoder.

What is claimed is: 
     
       1. A calibration bar, comprising:
 a target having a first end and a second end, and including alternating visual markers along a length of the target; 
 a first end plate coupled to the first end of the target; 
 a second end plate coupled to the second end of the target; and 
 a marker strip having a known lateral distance operably coupled to the first end plate, 
 wherein the first and second end plates are configured to position the target in place along a railroad track beneath a clearance level of a vehicle travelling along the railroad track. 
 
     
     
       2. The calibration bar of  claim 1 , wherein the first and second end plates include at least one attachment apparatus to couple the calibration bar to the railroad track. 
     
     
       3. The calibration bar of  claim 2 , wherein the attachment apparatus mechanically, electrically, or magnetically couples the end plates to the railroad track. 
     
     
       4. The calibration bar of  claim 1 , wherein the marker strip perpendicular to the roadway is a black strip. 
     
     
       5. The calibration bar of  claim 1 , wherein each visual marker of the alternating visual markers along the length of the calibration bar are a same length. 
     
     
       6. The calibration bar of  claim 1 , wherein the alternating visual markers along the length of the calibration bar alternate between at least two colors. 
     
     
       7. The calibration bar of  claim 5 , wherein the at least two colors include black and white. 
     
     
       8. A calibration bar system, comprising:
 a calibration bar including a target, a first and second end plate, and a marker strip having a known lateral distance; 
 an image capturing module coupled to a vehicle, wherein the image capturing module includes a camera operable to capture an image of the target; and 
 one or more controllers communicatively coupled to a vehicle encoder and the camera, wherein the one or more controllers are operable to: 
 determine a number of lateral pixels in a lateral pitch distance of the image of the target; 
 determine a lateral object pixel size based on the number of lateral pixels; 
 determine a number of longitudinal pixels in a longitudinal pitch distance of the image; and 
 compare the number of lateral pixels to the number of longitudinal pixels. 
 
     
     
       9. The calibration bar system of  claim 8 , wherein the one or more controllers are further configured to determine, in response to comparing the number of lateral pixels to the number of longitudinal pixels, that the number of lateral pixels matches the number of longitudinal pixels. 
     
     
       10. The calibration bar system of  claim 8 , wherein the one or more controllers are further configured to calculate a vehicle encoder rate based on a field calibration assessment. 
     
     
       11. The calibration bar system of  claim 10 , wherein the field calibration assessment includes a field calculation of the lateral object pixel size based on the number of lateral pixels and a determined number of pixels. 
     
     
       12. The calibration bar system of  claim 10 , wherein the one or more controllers are further configured to program the vehicle encoder rate into a vehicle encoder coupled to a wheel of the vehicle. 
     
     
       13. The calibration bar system of  claim 10 , wherein the vehicle encoder rate is based on a relation of a triggering factor, a wheel circumference, and the object pixel size. 
     
     
       14. The calibration bar system of  claim 8 , wherein the one or more controllers are further operable to determine, in response to comparing the number of lateral pixels to the number of longitudinal pixels, that the number of lateral pixels does not match the number of longitudinal pixels. 
     
     
       15. The calibration bar system of  claim 14 , wherein the one or more controllers are further operable to:
 resolve a difference between the number of lateral pixels and the number of longitudinal pixels using new calibration information to calibrate the image capturing module; and 
 transmit the new calibration information. 
 
     
     
       16. The calibration bar system of  claim 8 , wherein the camera of the image capturing module is further operable to adjust its focus on the target under constant lighting conditions to obtain a maximum contrast between two pixels that identify a boundary of light and dark portions of the target. 
     
     
       17. The calibration bar system of  claim 8 , wherein the target includes an alternating pattern of a plurality of black and white sections. 
     
     
       18. The calibration bar system of  claim 17 , wherein:
 the lateral pitch distance represents a width of an end plate coupled to the target; and 
 the longitudinal pitch distance represents a length of one section of the plurality of black and white sections.